s3c2440_adc.c

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <mach/regs-clock.h>
#include <plat/regs-timer.h>
    
#include <plat/regs-adc.h>
#include <mach/regs-gpio.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>

#include "s3c2440_adc.h"

#undef DEBUG
//#define DEBUG

#ifdef DEBUG
#define DPRINTK(x...) {printk(__FUNCTION__"(%d): ",__LINE__);printk(##x);}
#else
#define DPRINTK(x...) (void)(0)
#endif

#define DEVICE_NAME    "adc"

static void __iomem *base_addr;

typedef struct {
    wait_queue_head_t wait;
    int channel;
    int prescale;
}ADC_DEV;

DECLARE_MUTEX(ADC_LOCK);
static int OwnADC = 0;

static ADC_DEV adcdev;
static volatile int ev_adc = 0;
static int adc_data;

static struct clk    *adc_clock;

#define ADCCON (*(volatile unsigned long *)(base_addr + S3C2410_ADCCON))    //ADC control

#define ADCTSC (*(volatile unsigned long *)(base_addr + S3C2410_ADCTSC))    //ADC touch screen control

#define ADCDLY (*(volatile unsigned long *)(base_addr + S3C2410_ADCDLY))    //ADC start or Interval Delay

#define ADCDAT0 (*(volatile unsigned long *)(base_addr + S3C2410_ADCDAT0))    //ADC conversion data 0

#define ADCDAT1 (*(volatile unsigned long *)(base_addr + S3C2410_ADCDAT1))    //ADC conversion data 1

#define ADCUPDN (*(volatile unsigned long *)(base_addr + 0x14))    //Stylus Up/Down interrupt status


#define PRESCALE_DIS (0 << 14)
#define PRESCALE_EN (1 << 14)
#define PRSCVL(x) ((x) << 6)
#define ADC_INPUT(x) ((x) << 3)
#define ADC_START (1 << 0)
#define ADC_ENDCVT (1 << 15)

#define START_ADC_AIN(ch, prescale) \
    do{ \
        ADCCON = PRESCALE_EN | PRSCVL(prescale) | ADC_INPUT((ch)) ; \
        ADCCON |= ADC_START; \
    }while(0)


static irqreturn_t adcdone_int_handler(int irq, void *dev_id)
{
    if (OwnADC) {
        adc_data = ADCDAT0 & 0x3ff;

        ev_adc = 1;
        wake_up_interruptible(&adcdev.wait);
    }

    return IRQ_HANDLED;
}

static ssize_t s3c2410_adc_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{
    char str[20];
    int value;
    size_t len;
    if (down_trylock(&ADC_LOCK) == 0) {
        OwnADC = 1;
        START_ADC_AIN(adcdev.channel, adcdev.prescale);
        wait_event_interruptible(adcdev.wait, ev_adc);

        ev_adc = 0;

        DPRINTK("AIN[%d] = 0x%04x, %d\n", adcdev.channel, adc_data, ADCCON & 0x80 ? 1:0);

        value = adc_data;
        sprintf(str,"%5d", adc_data);
        copy_to_user(buffer, (char *)&adc_data, sizeof(adc_data));

        OwnADC = 0;
        up(&ADC_LOCK);
    } else {
        value = -1;
    }

    len = sprintf(str, "%d\n", value);
    if (count >= len) {
        int r = copy_to_user(buffer, str, len);
        return r ? r : len;
    } else {
        return -EINVAL;
    }
}

static int s3c2410_adc_open(struct inode *inode, struct file *filp)
{
    init_waitqueue_head(&(adcdev.wait));

    adcdev.channel=0;
    adcdev.prescale=0xff;

    DPRINTK( "adc opened\n");
    return 0;
}

static int s3c2410_adc_release(struct inode *inode, struct file *filp)
{
    DPRINTK( "adc closed\n");
    return 0;
}


static struct file_operations dev_fops = {
    owner:    THIS_MODULE,
    open:    s3c2410_adc_open,
    read:    s3c2410_adc_read,    
    release:    s3c2410_adc_release,
};

static struct miscdevice misc = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &dev_fops,
};

static int __init dev_init(void)
{
    int ret;

    base_addr=ioremap(S3C2410_PA_ADC,0x20);
    if (base_addr == NULL) {
        printk(KERN_ERR "Failed to remap register block\n");
        return -ENOMEM;
    }

    adc_clock = clk_get(NULL, "adc");
    if (!adc_clock) {
        printk(KERN_ERR "failed to get adc clock source\n");
        return -ENOENT;
    }
    clk_enable(adc_clock);
    
    /* normal ADC */
    ADCTSC = 0;

    ret = request_irq(IRQ_ADC, adcdone_int_handler, IRQF_SHARED, DEVICE_NAME, &adcdev);
    if (ret) {
        iounmap(base_addr);
        return ret;
    }

    ret = misc_register(&misc);

    printk (DEVICE_NAME"\tinitialized\n");
    return ret;
}

static void __exit dev_exit(void)
{
    free_irq(IRQ_ADC, &adcdev);
    iounmap(base_addr);

    if (adc_clock) {
        clk_disable(adc_clock);
        clk_put(adc_clock);
        adc_clock = NULL;
    }

    misc_deregister(&misc);
}

EXPORT_SYMBOL(ADC_LOCK);
module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");



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